Ellipsograph



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ELLIPS OGRAPH Filed Oct. ll. 1924 wwf .L .X MAME Tfn/1n M2M VMNTV N HH F Inm L55 MW SY L6 E N Patented Oct. 4, 1927i UNITED STATES PATENT` OFFICE;

ELLIPSOGRAPH.

' Application filed Octoberr 11, 1924. Serial No. 743,104.

This invention has for its object to provide an extremely simple but highly eiiicient tool for drawing ellipses of various sizes.

It is a further object to provide a device for drawing an ellipse which will permit of the speedy regulation of the device to draw an ellipse of desired major and minor axes.

It is a more. specific object of the invention to provide an ellipsograph consisting of a T-shaped member having a straight edge along its top side, and a guideway in the stem of the T at right angles thereto, and a scribing arm having members adapted to engage said guideway and said straight edge to generate an ellipse from a tracingpoint on said arm when said arm is properly manipulated.

These and other objects of the invention will be apparent from the following description made in connection with the accompanying drawings wherein like characters refer to similar parts throughout the'several views, and in which,

Fig. 1 is a plan view of the device with the moved position of some of the parts shown in dotted lines;

Fig. 2 is a side elevation oi the invention with the scribing arm in alignment with the minor axis of the ellipse to be drawn, some parts being broken away;

Fig. 3 is a plan view of the scribing arm detadlied; and

Fig. 4 is a vertical section taken on the line 4-4 of Fig. 2.

Referring to the drawings, therinvention comprises two parts, one, a T-shaped member and the other a scribing arm or tool adapted to be manipulated and guided by said T-shaped member. The T-shaped inem` ber has a straight edge 5 along its top side, one side of which is graduated from a central point therealong. ,The stem o i' the T-shaped member 6 is provided with a guideway 7, preferablvin the form of a groove, extending at right angles to the straight edge 5. The scribing arm preferably comprises two telescoping members 8 and 9, the member 8 having a split end 10 with a socket therein adapted to resiliently hold a tracing point 11. A set screw 12 permits the member 8 to be rigidly secured to member 9 in a desired telescoped position. .A pair of guide pins 13 and 14 are slidably mounted on the member 9 of the scribing arm which are equipped with set screws 15 and 16 adapted to rigidly secure said pins to the member 9 at desired positions thereon. The members 13 and 14 are adapted to engage, respectively, the straight edge 5 and the guideway 7 of the T-shaped member.

Operation.

The end. of the pin 14 is inserted inl pin 13 is pressed against and moved along y the straight edge of the T-shaped member from side to side. The movement of the scribing arm will cause the scribing point to draw a complete half .of an ellipse, as shown in Fig. 1. The T-shaped member may then be inverted with the straight edge along the major axis of the ellipse to be drawn, as before, and the operation repeated the telescoping member 8 a wide range is permitted in the size and proportions of ellipses capable of being drawn with the de- VlCe. 2

The instrument works with great precision, is easily handled and set and may be used for inking if the curve drawn is not very flat. The scribing point 11 will draw a substantially perfect ellipse if the pins are properly confined and moved in the guideway and along the straight edge respectively.

Obviously the device comprises extremely few parts and may be manufactured at little cost.

It will be understood that various changes in the form, details and arrangements of the parts may be made without departing from the scope of the invention.

What is claimed is:

An ellipsograph comprising a l substantially iiat member having an elongated rectilinear guide and having a groove extending to draw the other haltof the ellipse. With 'jg y 1,644,205

from the mid-point of said guide and at seriber carrying member adapted to teleright angles thereto, a hollow seribing arm, scope Within said seribing arm.

a. pin slidable on said arm and adapted to In testimony whereof We ax our signa- 10 engage `said rectilinear guide, means for tures.

'if rigidly securing said pin With said scifibing OLAF RETTEDAL. NELS JOSEPH NELSON.

arm, a second pin mounted on said soribing 2mm adapted to engage said groove and a 

